# [EVDL] Volt versus Prizm, the matchup :-)

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Well, my dad picked up his volt last weekend. Very impressive car to say
the least, I drove it in electric mode and had it up to 95mph in full
electric mode in short order. It has the slight "sag" in power at around
60-70, then picks up to 90 as the secondary electric motor kicks in to help.

Impressive.

Anyway, this morning I drove his insight back from my house to his (I
had to drive it home from the dealership) and we took a run from his
house to mine. I've done this run many times with my 1994 US Electricar
Prizm (50kw, 300v pack, 52ah capacity AGM) and it takes a good 23 ah of
current to make the run from his house to mine. He and I both have 6.6kw
Magnechargers, so I can make the trip up, charge for 2 hours, and make
it back.

The Volt's battery capacity is 16kw-hrs raw, 10.4kw hrs usable. So I
will assume that the gauges calculate based on the 10.4kw.

The Prizm has a [email protected] or 15.6kw pack. Usable capacity at 60a
draws (highway speed) is 12.6kw to empty. Using the 20% reserve capacity
rule (discharge to 80%) we get a usable capacity of 10.08kw.

On the drive to the house, the Volt covered the distance using 70% of
it's usable battery capacity. Based on it's pack capacity of 10.4kw
usable that put it at 7.280 kw used.

The Prizm making the same run uses [email protected] (average) to go the exact
same distance. That works out to 6.9kw/hr.

So for a rough estimate, it looks like the Volt uses about as much power
as the Prizm. Given that they are about the same shape and weight (I'm
guessing the motor weighs about 700 pounds plus 300 for the pack would
compare to the 1,100 pounds for the Prizm pack) that once again makes sense.

Unfortunately the Volt does *not* come equipped with a Class II
Magnecharger port, so he could not do a quick recharge at my house. I do
not know why But he can use the gas engine to get home.

Come springtime we'll have to drag race each other a bit.

Chris

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On 8 Jan 2011 at 13:27, Christopher Zach wrote:

> So I will assume that the gauges calculate based on the 10.4kw.
>
> The Prizm has a [email protected] or 15.6kw pack. Usable capacity at 60a
> draws (highway speed) is 12.6kw to empty. Using the 20% reserve capacity rule
> (discharge to 80%) we get a usable capacity of 10.08kw.
>
> On the drive to the house, the Volt covered the distance using 70% of
> it's usable battery capacity. Based on it's pack capacity of 10.4kw
> usable that put it at 7.280 kw used.
>
> The Prizm making the same run uses [email protected] (average) to go the exact
> same distance.

s/kw/kWh/g

> That works out to 6.9kw/hr.

s/kw\/hr/kWh/

For those who don't speak sed*, that's a reminder that the correct unit for
EV energy usage is the kiloWatt hour, abbreviated kWh. (Mis)using kW for
that purpose is like saying that you just filled your ICEV's gas tank with
20 horsepower.

I don't mean to be snarky or anything. I'm sincere here, trying to see that
the list archive reflects the correct units of EV energy-use measurement. I
think we EV hobbyists damage our own credibility as a group when we aren't
reasonably careful with our nomenclature.

It only takes one more keystroke to type the correct unit abbreviation,
folks, so please try to be accurate - if only for the sake of the newbies

Thanks.

PS - Christopher, thanks for posting the comparison. It's interesting that
the Volt, a fairly complex and heavy car, comes so close to the Prizm
conversion in energy use.

Now it would be nice to know what the distance was, so we'd have a real-
world kWh/mi figure for the Volt.

I would also suggest that you measure the usage several times and average,
so as to partially compensate for variable conditions.

-----

*The *nix text stream editor. The command shown globally substitutes the
string "kWh" for the string "kw". The syntax also applies to other *nix
editing utilities.

David Roden - Akron, Ohio, USA

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> PS - Christopher, thanks for posting the comparison. It's interesting that
> the Volt, a fairly complex and heavy car, comes so close to the Prizm
> conversion in energy use.

*Nod* It sort of makes sense. The Prizm with the pack might weigh about
as much as the Volt, and the Prizm is actually rather aerodynamic.
They're also 4 door cars, although the Prizm does have space for a fifth
person.
I took a nice picture of the two of them together, side by side. It's
interesting to see what changes and what stays the same

> Now it would be nice to know what the distance was, so we'd have a real-
> world kWh/mi figure for the Volt.

I think it was 26 miles, I'll check with the dad. However it is
"downhill" a few hundred feet overall since I am by the bay and Dad is
up in Timonium MD. I have found that the run out to his house pulls
about 30ah from the Prizm's pack, so it is somewhat more to get there
than back.

His driving with the Insight mirrors this. Charges the battery on the
way down, kills it on the way back.

> I would also suggest that you measure the usage several times and average,
> so as to partially compensate for variable conditions.

Well, for miles it's not too accurate, the change in elevation makes a
big difference on the Prizm and probably the Volt as well. Also my
calculations are still kind of "barn door" as we have not installed an
E-meter in the Volt.

Yet.

But comparing cars head to head is interesting. I'd bet a leaf would be
similar.

Chris

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